(CNN) In late February, days before Russian forces launched an all-out invasion of Ukraine, videos and photos began circulating on social media showing tanks, communications trucks and rocket launchers emblazoned with the letter "Z" rolling toward the border.
Digital sleuths speculated over what the "Z," written in the Roman alphabet rather than Cyrillic, might indicate about Moscow's next moves.
Military experts interpreted the "Z" as "Za pobedy," Russian for "for victory," or as "Zapad," for "West." Some dubbed vehicles painted with the symbol the "Zorro Squad," while others suggested the "Z" might stand for the Kremlin's self-styled "target number one," Ukrainian President Volodymyr Zelensky.
Aric Toler, a researcher with Bellingcat, an open source investigative operation that has been monitoring Russian military operations since Moscow fomented a war in eastern Ukraine eight years ago, said on February 20 that the group had no idea what the "Z" symbol meant and had not seen it used before. "So, assume the worst, I guess/fear," he wrote on Twitter.
Russian defense policy expert Rob Lee, who has been tracking the "Z" vehicles since troops began massing on Ukraine's doorstep, suggested the symbol might refer to military contingents assigned to the fight in the country. "It appears Russian forces near the border are painting markers, in this case 'Z', on vehicles to identify different task forces or echelons," Lee, a PhD student at King's College London's War Studies Department, tweeted on February 19.
But in the days since Moscow ordered the bloody assault on Ukraine, what started as a mysterious military symbol has become a sign of popular support for the war in Russia, and what analysts describe as the unfurling of a chilling new nationalist movement.
Russians have daubed the "Z" on their cars, sported black hoodies emblazoned with the symbol, and fashioned makeshift "Z" brooches on lapels -- a sign that there is some popular support for Russian President Vladimir Putin and his efforts to expand Moscow's sphere of influence by seizing parts of Ukraine.
"Authorities launched a propaganda campaign to gain popular support for their invasion of Ukraine and they're getting lots of it," Kamil Galeev, an independent researcher and former fellow at the Wilson Center, a non-partisan policy think tank in Washington, DC, wrote in a comprehensive Twitter thread on the use of the "Z" symbol in propaganda videos and by Russians on social media.
"This symbol invented just a few days ago became a symbol of new Russian ideology and national identity," Galeev added.
As the Kremlin tightens its grip on any news of Russian casualties or setbacks making its way back home -- enforcing an extraordinary new law that makes the spread of "fake" information an offense punishable with jail terms -- Putin's backers are ramping up their support for the war.
At a hospice in Kazan, a city in Russia's southwest Tatarstan region, children dying from cancer were asked to line up in a "Z" formation outside in the snow to show their support for the Russian military operation.
"Our patients and entire team took part in it, about 60 people in total. People lined up in the form of the letter 'Z,'" Vladimir Vavilov, the chairman of a cancer charity that runs the hospice, said in a statement. "In our left hand we held leaflets with the flags of the LPR, DPR, Russia and Tatarstan and we clenched our right hand into a fist."
Vavilov was referring to the Luhansk People's Republic and the Donetsk People's Republic, separatist-held areas of eastern Ukraine that Putin recognized last month as independent states as part of a pretext for invading the country.
The "Z" symbol has also cropped up among members of Russia's lower house of Parliament, the Duma.
Maria Butina was convicted of serving as an unregistered foreign agent in the United States trying to infiltrate prominent conservative political circles before and after the 2016 election. She now represents the Kirov region for the Putin-supporting United Russia political party, and has backed the war in posts on her Telegram channel.
Butina took to the platform to share a clip of herself drawing a white "Z" on the lapel of her blazer, and has updated her profile to a selfie in a black T-shirt with a white letter "Z."
"Keep up the work, brothers. We are with you. Forever," she said in the video clip, clenching her fist.
Correspondents reporting from Ukraine for Russian state-owned news network Rossiya-24 have sported the "Z" on flak jackets.
Footage from Russia's main cities shared over the weekend captured convoys of cars with white "Z"s taped to windows, honking horns and flying huge Russian flags. At the Gymnastics World Cup in Doha, Qatar, Russian athlete Ivan Kuliak sported the insignia on the medals podium as he stood beside Ukraine's Illia Kovtun, the gold medalist.
And in two slickly produced propaganda videos circulating on social media, young Russians wearing black T-shirts and hooded sweatshirts emblazoned with the letter "Z" and hashtag #СвоихНеБросаем, or "we don't abandon our own (guys)," wave Russian flags and voice their support of Putin's war, chanting: "For Russia, for the president. For Russia, for Putin!"